1. DNA Structure Unit 2-1 Notes Mr. Hefti – Pulaski Biology Unit 2-1 Notes Mr. Hefti – Pulaski Biology

4. DNA = blueprint for life A. DNA = blueprint for life All living things possess DNA Located in the nucleus Chemical instructions for structure and function Unique code tells cells what to do

5. B. DNA is a “double helix” Think - twisted ladder There’s a left and right side chemically bonded together in the middle Held together by hydrogen bonds

6. C. DNA made of repeating units called nucleotides Here are the 3 parts of a nucleotide: (please draw in notes)

7. D. Phosphate Made of H, O and P Phosphate links nucleotides together

8. E. Deoxyribose sugar 5 carbon sugar (pentagon shaped) Made of C, H and O Deoxyribose links phosphate and nitrogenous base

9. F. Nitrogenous base Made up of C, H, O and N Form rungs of ladder 4 types: – Adenine (A) – Thymine (T) – Guanine (G) – Cytosine (C)

10. G. Base-pairing rules A always pairs with T C always pairs with G

11. H. In conclusion… The combination of As, Ts, Cs, and Gs is what makes each organism unique Human DNA composed of 3 billion repetitions of those same 4 letters